Typewriter



J. C. REDDICK July 15 TYPEWRITER Filed DeC. 23. VA,

lNVfl/VTOR JOIN QRz-iDp/c Patented July 15, 1924.

JOHN COATSWORTH REDDICK, OF TORONTO, ONTARIO,

'IYPEWRITER.

Application filed December 23, 1922. .Serial No. 608,757.

To all whom it may concern:

Be itknown that 1, JOHN COATSWORTH 'REDDICK, a subject of the King of Great Britian, and aresident of the city of Toronto, in the county of York, in the Province of Ontario, Canada, have invented certain new and useful Improvements in Typewriters, of which the following is a specification.

My invention relates to improvements in typewriters and the object of the invention is to devise a simple means readily applied for deadening oreliminating, as far as'possible, sound or noise produced by im- 5 pact of the type bars of a writing machine upon the platen =or stop ring during the striking of the blow and it consists essentially of a strip of resilient material supported so as to lie in the path of travel to the printing point of the type bars to con-' trol or limit the time during which each type bar has impact upon the platen and upon the stop ring of the segment so as to produce a short, sharp, quick blow thereby preventing the vibrations produced in the type bars by. the blow from acting while in contact with the printing surface or with the stop ring of the segment plate and thereby being converted into sound as hereinafter more particularly explained by the following specification.

Fig. 1 is a perspective View of a segment plate provlded with the usual stop ring or rib and with my resilient limiting device applied thereto.

Fi 2 is a perspective detail of my limitevice separated from the segment.

ig. 3 is a sectional view on line 3-3, Fig. 1 and showing a type bar in position. Fig. 4 is a perspective view of a segment plate showing an alternative form of resilient limiting device.

Fig. 5 is a perspective detail of the form of limiting device shown in Fig. 4: separated from the segment.

In the drawings like characters of reference indicate corresponding parts in each figure.

1 indicates a segment ployed in typewriters wood, which plate is provided with what is known as a stop ring 2 against which the type bars 3 contact as the blow .upon the printing surface is struck by the type so as to prevent the full force of the blow plate commonly em such as the Underbeing received by theplaten. The type bars 3 are pivotally mounted in the usual manner upon the wire 5 held within a groove 6, (see Fig. 3).

' Under ordinary conditions when the type strikes the surface of the platen at the printing point it remains in contact for a space of time sufiicient for the vibrations which are produced in the type bar by the striking of the blow to be transmitted to such printing surface and thereby be converted into sound.

In order to overcome this defect I have devised means by which immediatel the type of the type bars strikes the printing surface it rebounds therefrom before the vibrations produced by the blow have time to actupon the platen surface, such vibrations, as soon as the contact is broken, being diffused in the air so as to prevent their conversion into sound.

-I will now describe the means by which the. aforesaid defect is overcome.

In the recess formed between the stop ring 2 and outer portion 7 of the plate 1 a recess 8is formed. 9 are the securing screws by which the-segment plate is secured in position on the typewrite I utilize the screws 9 for securing m device in position, such device consisting o a metallic plate or strip 10 arc-shaped in form so as to fit in the bottom of the recess 8 and around the stop ring 2. The plate 10 is provided with orifices 11 throu h which the securin screws 9 extend. 12 1s a sheet or strip 0 solid but fairly soft rubber which is also arc-shaped in form to fit upon the plate 10 and around the stop ring 2. y

The strip of rubber 12 is of such a thickness that the outer surface thereof is located above the level of the surface of the stop ring 2 so that when the type bar 3 strikes its blow it first comes into contact with the strip 12 so as to compress it, the blow being finall limited by the stop ring 2. Immediate y this blow is struck and definitely stopped by the stop ring 2 the strip 12 whic has been compressed by the blow as aforesaid then acts by reason of its resilienceto carry the type of the ty e bars away from the platen so that immediately the imprint ofthe type has been made the type will be instantaneously carried away from and out of contact with the printing surface and thereby prevent the vibrations produced in its the type bar by the blow from acting on the surface of the platen and thereby producing sound.

By the instantaneous breaking of the contact the effect of the vibrations upon the printing surface producing a chattering which is the direct cause ofthe sound produced is eliminated, the effect of such vibra tions as soon as a contact is broken being dissipated in the air. The strip' 12 may be 'rovided with a recess or cut out portion 13 or the passage of the guide bar.

In Figures 4 and 5 I have shown an alternative form in which the metal base plate 8" is cut away between the securing screws 9*, the rubber strip 12 carried thereby being also cut to a corresponding shape to form a narrow contacting rib-like portion 13 with which the type bars engage.

It may be stated that cylinders or platens with soft rubber interiors are now being used but they do not fulfill the requirements for the reason that the majority of the sound is caused by a lingering contact between the type face of the type bar and the cylinder or platen.

There is also further noise produced in machines using a segment plate at the point where the type bar comes in contact with the stop ring which is generally located on the face of the segment plate about one inch above the line of the fulcrum or bearing wire 5. This noise is also mostly due to a lingering contact between the striking suraces.

What I claim as my inventionisr 1. In a bars, two members located in the path of travel of the type bars having respectively an unyielding type bar contact surface and a yielding type bar contact surface located in advance of the unyielding contact surface.

2. In a typewriter provided with type bars and platen, a stop member having a yielding bar contact surface and a hard member so disposed in relation to the yielding surface as to produce initially a type bar contact with the yielding surface, then a type face contact with the platen, type bar contact with the hard membe'r.

3. In a typewriter provided with type. bars, a hard metal stop plate, a resilient stop carried by the plate in such a position as to be. partially compressed by the type bar as the type bar strikes the plate after it arrives at its platen engaging position.

and finally a typewriter provided with type r 4. In a typewriter provided with type bars, a'hard metal stop ring and a resihent arcuate stop concentric with and in advance of the stop ring and with which the type bars successively contact.

5. In a device of the class described, a plate provided with a stop ring and a resilient stop having its contact face in advance of the contact face of the stop ring.

6. In a typewriter, the combination with the segment plate provided with a stop ring, and a resilient piece adapted to fit against the segment stop rin outward beyond suc JOHN COATSWORTH REDDICK.

stop ring.

and projecting slightly 

